BCHM 10000 Lecture Notes - Lecture 11: Aromatic Amino Acids, Sulfur, Heart Valve
27 Jun 2018
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Polarity
Electronegativity Difference
(between the two atoms)
•Polarity is a term that
describes how electrons are
shared or transferred
between two atoms
•A molecule is polar if there is
an unequal distribution of
charge (based on
electronegativity differences
or shape)
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Electronegativity
the tendency of an atom to attact electrons
A bond between C and O is a _________
because the difference in electronegativity
is ________.
A bond between Na and Cl is a _________
because the difference in electronegativity
is ________.
A bond between C and H is a _________
because the difference in electronegativity
is ________.
Is CO2 polar or nonpolar?
Is H2O polar or nonpolar?
Electronegativity Difference (between the two atoms)
Molecular shape
polar
1
2.1
nonpolar
.4
polar
nonpolar
n ionic
can bond w/ 3 different
atoms b/c it bonds w/ 4
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•Biological processes are based upon carbon
chemistry and occur in a largely aqueous
environment.
•Water is a unique solvent whose properties
are extremely important to biochemistry.
•Water is a dipole because of its geometry and
the difference in electronegativity between
hydrogen and oxygen (and nitrogen).
•In water, the hydrogen atoms have a partial
positive charge, and the oxygen atom has a
partial negative charge and this permits
hydrogen bonding.
Water and hydrogen bonds
BCHM 100 Weeks 5 - 6
inter =
intra = covalent/ionic bonds
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Document Summary
Polarity: polarity is a term that describes how electrons are shared or transferred between two atoms, a molecule is polar if there is an unequal distribution of charge (based on electronegativity differences or shape) Electronegativity the tendency of an atom to attact electrons. A bond between c and o is a _________ because the difference in electronegativity is ________. polar. A bond between na and cl is a _________ because the difference in electronegativity is ________. n ionic. A bond between c and h is a _________ because the difference in electronegativity is ________. can bond w/ 3 different atoms b/c it bonds w/ 4 nonpolar. Water and hydrogen bonds: hydrogen bonds are weak, energy in covalent bonds ~400 kj mol-1, energy in hydrogen bonds ~20 kj mol-1, the average lifetime of a hydrogen bond in liquid water is around 10-12 seconds.
